Ilan A Yaeger
Aim: The basic single-artery fractional flow reserve (FFR) method can deal with stenoses located within just one artery (exposed proximally to the aortic pressure) or with several independent suchlike arteries (like in the FAME study) that can be treated one at a time. It cannot handle trans-arterial stenosis-stenosis interactions. The aim of this article is to provide the advanced Multi-artery FFR method with the capability of resolving all-stenotic 3-artery configurations in the presence of considerable stenosis-stenosis interactions. Methods and results: The Multi-artery FFR method does take into account inter-arterial stenosis-stenosis interactions. Employing resistances of analogical formations of electrical resistors, the method has been adapted in this article to provide exact resolutions (to within ΔFFR= ± 0.02) of all-stenotic 3-artery configurations of sizable arteries in the low and in the intermediate stenosis severity ranges. Unlike in the single artery case, because of trans-arterial stenosisstenosis interactions, the actual FFR (denoted FFRreal) of an artery within the stenotic 3-artery configuration is no longer equal to the familiar FFRtrue of the artery in its stand-alone position (with other arteries virtually stenosis-free). The difference between FFRtrue and FFRreal of an artery (derived from intracoronary pressures at designated points of the configuration) may be even about 0.20 (!) which is substantial and intuitively unexpected (an example of sizable arteries of the configuration with FFRtrue~0.90 and FFRreal~0.70 is presented). The Multiartery FFR method can also predict outcomes (in terms of FFRreal) of possible revascularizations for obtaining the optimal resolution. Conclusion: The basic FFR method may yield the FFRtrue of an artery. In a standalone position it may pass as 'not a risk' but when it is part of an all-stenotic arterial configuration it may be graded 'a very high risk' because of its possibly very low FFRreal due to stenosis-stenosis interactions with other members of the configuration.
